1. Field of the Invention
The present invention relates to a liquid ejection head such as an ink jet recording head from which an ink is ejected on a recording medium to conduct recording.
2. Description of the Related Art
Examples of use of a liquid ejection head for ejecting a liquid include an ink jet recording head used in an ink jet recording system in which an ink is ejected on a recording medium to conduct recording. As the ink jet recording head (recording head), a recording head having an ejection device substrate and an ink supply path forming member (ink supply member) that supplies an ink to the ejection device substrate is known. Incidentally, the ejection device substrate is provided with at least a plurality of ejection orifices for ejecting an ink and an energy-generating element for applying ejection energy to the ink within a flow path. A silicon substrate is generally used as a substrate used in the ejection device substrate. The ink supply member is made of a plastic or the like.
Such a recording head has heretofore involved the following problem. A stress against a joint interface between the ejection device substrate provided with the energy-generating element for ejecting a liquid from the ejection orifice and the ink supply member for storing the liquid and supplying the liquid to the ejection device substrate has been increased by a difference in coefficient of linear expansion between the substrate and the member, so that warpage or distortion of the ejection device substrate may have occurred in some cases.
In such a case, a thermal stress may have been generated at the joint interface between the ejection device substrate and the ink supply member by temperature rise during recording in some cases, and deformation of the ejection device substrate may have been caused in some cases to affect a recorded image.
As a method for solving the above-described phenomenon, U.S. Pat. No. 6,257,703 describes such a construction that a support member having a coefficient of linear expansion comparable to that of the silicon of the ejection device substrate is caused to intervene between the ejection device substrate and the ink supply member. In addition, Japanese Patent Application Laid-Open No. 2007-276156 discloses a method for integrally forming a support member having a coefficient of linear expansion comparable to that of the silicon of the ejection device substrate with the ink support member.
Such a recording head having the support member between the ejection device substrate and the ink supply member as described above has caused leakage of an ink toward the outside of a flow path unless the ejection device substrate or the ink supply member has been surely joined to the support member. In particular, when the support member has at least two ink supply flow paths, there has been a possibility that two or more inks may mix with each other to affect a recorded image when this joint is not surely conducted to leak the ink to the outside of the flow paths.
Since the joint between the substrate and the support member easily affects the recorded image, they are generally joined by a mount technology attaching great importance to accuracy to guarantee liquid sealability.
On the other hand, in the joint between the support member and the ink supply member, a joint method by simple integral molding is favorable because the influence on the recorded image is slight. However, a material used in the ink supply member and a material used in the support member are different in properties required, so that a good joint state may have not been achieved in some cases when the support member has been formed integrally with the ink support member. In addition, peeling may have occurred between the support member and the ink supply member in some cases, and so there has been a possibility that the liquid sealability may be lowered.
A method of improving joining ability by providing a depressed and projected profile on a joint surface between the support member and the ink supply member is considered as a method for improving the liquid sealability. However, it is required to produce more silicon substrates from one wafer from the viewpoints of energy saving and cost lowering, and researches for improving the number of substrates producible from one wafer are advanced. In the process thereof, as the width of the substrate is more narrowed, a joint region between the substrate and the support member and a joint region between the support member and the ink supply member also tend to be narrowed. With the narrowing of the joint region between the support member and the ink supply member, it is difficult to provide the depressed and projected profile on the joint surface between the support member and the ink supply member by molding.
Accordingly, there is a demand for ensuring a region capable of providing the depressed and projected profile on the joint surface between the support member and the ink supply member even when the substrate narrowing technology is advanced to guarantee liquid sealability in integral molding of the support member and the ink supply member.
The present invention can solve the problems in the prior art. The present invention can provide a liquid ejection head having good liquid sealability, such as an ink jet recording head, in which a support member supporting an ejection device substrate and an ink supply member for supplying an ink to the ejection device substrate are joined with extremely good compatibility, even when the substrate narrowing technology is advanced.